The police have registered a criminal case against Pattali Makkal Katchi founder leader Dr S Ramadoss and his son Union Health Minister Anbumani Ramadoss, among others, in connection with the murder of the aide of Tamil Nadu Minister C V Shanmugam in Tindivanam on Monday night.

A 15-member armed gang, after making a vain bid on Shanmugam's life at his residence, stabbed his aide Muruganandam.

On a complaint lodged by Shanmugam with the Roshnai police station limit, the police registered the case with Ramadoss as prime accused and Anbumani Ramadoss as second accused.

Others who were arraigned in the case are Parasuraman, son in law of Dr Ramadoss (A3), Srinivasan (A4), Karunanidhi (A5), PMK nominee pitted against Shanmugam in the Tindivanam Assembly constituency, Raghu (A6) and Pradeepan (A7), grandson of Ramadoss, police said.

All the seven accused were charged under Sections 147, 148, 323, 324, 307, 506 (II) and 120 (b) of the Indian Penal Code. The police have arrested no one so far.

Meanwhile, Inspector-General of Police Jangid and Deputy Inspector-General of Police Sanjay Arora visited Shanmugam at his residence. Security has been beefed up at the minister's house.

Meanwhile, Ramadoss described as "political vendetta", the police action of registering a first information report against his son, Union Health Minister Dr Anbumani Ramadoss, and himself for allegedly instigating the murder.

In a statement, he alleged that the FIR was filed under pressure from Shanmugham and said that police should not succumb to pressure from a government, "which would be voted out of power in a couple of days".

The police, instead of filing a case against them, should find out the real culprits, he said.

He said he did not approve of violence and added that an FIR should be filed only after proper investigation.

With PTI inputs